Nothoceros aenigmaticus, collected in North Carolina. Note the elongated eggs inside of the thallus, probably from a damselfly (K. Tennessen, pers. com.). More studies are needed to verify the identity of the insect. See Chinquapin. 2009. 17 (1).

DISSERTATION RESEARCH

I am interested in the diversification and biogeographical distribution patterns of hornworts especially the Nothoceros alliance (including the Megaceros from the American Continent). My dissertation research is focusing on the major evolutionary events leading to the lack of sexual reproduction in the Southern Appalachian (SA) endemic and asexual hornwort Nothoceros aenigmaticus . The species is the only member of the genus in North America and there are no reported observations of sporophyte production. In the SA region male and female plants live ~ 30 miles apart and male plants produce depauperate antheridia (for unknown reasons sperm cells are unable to develop functional flagella).
The proposed research has three main objectives:

1) Reconstruct the phylogenetic origin and timeframe of the loss of sexuality in N. aenigmaticus.
2) Assess the population genetic structure of clonal populations of N. aenigmaticus using microsatellites.
3) Estimate the molecular signature in the transition to asexuality using nuclear coding regions.
4) Transcriptomic and genomic data of N. aenigmaticus.

The first aspect of my research is unraveling the phylogenetic origin of N. aenigmaticus and its closest Neotropical relative using a multi-locus approach.
I am also testing for any cryptic sexual recombination using microsatellites and exploring the genetic consequences of the lack of sex in the population dynamics of the SA populations. In addition I will be comparing patterns of genotypic diversity between SA populations and putative conspecific and sexually reproducing populations from tropical alpine regions. Given the potential extinction threat due to the Muller's ratchet effect (accumulation of deleterious mutations), this study will have conservation and evolutionary implications. The haploid nature of Nothoceros aenigmaticus makes the hornwort more vulnerable to deleterious mutations since no other allele is present in the gametophyte. (more details soon).

Using next generation technology (454 Roche) I will be exploring genomic and transcriptomic data from the gametophyte of this species (more details soon).

Lagunas de Zempoala, Morelos, Mexico. A Pleistocene sleeping volcano

RESEARCH GRANTS

This research has beeen funded by the the National Science Foundation (Doctoral Dissertation Improvement Grant, http://www.nsf.gov/awardsearch/showAward.do?AwardNumber=0910258); Ronald Bamford Fund, EEB Department, UCONN; International Association of Bryologists; International Association of Plant Taxonomists; Aaron J. Sharp Fund (University of Tennessee) and Southern Appalachian Botanical Society.

CURRENT INTERESTS

Systematics, anatomy, ultrastructure, molecular evolution and biogeography of hornworts (Anthocerotophyta), especially American taxa. Dating, population genetics, genomic evolution and genetic implications of the loss of sex in bryophytes.

Other interests are the evolution of carbon concentration mechanisms in the hornwort chloroplast, especially the ultrastructural and physiological implications of the presence of an algal-like pyrenoid. Chloroplast genomes in bryophytes and effect of level of RNA editing in hornworts. An increasing interest is the evolution of transcriptomes in hornworts.

- A.J. Sharp Award (American Bryological and Lichenological Society)
Best student paper at the annual meeting of the American Bryological and Lichenological Society, Providence, RI. $500.

- Sullivant Award from the American Bryological and Lichenological Society for the best paper published in the Bryologist during the year 2007 for the paper " Progress and challenges toward developing a phylogeny and classification of the hornworts" . The Bryologist, 110: 214-243 by Duff, R.J., J.C. Villarreal, D.C. Cargill & K.S. Renzaglia.

Early Land Plants Today/Encyclopedia of Life (World Meeting of Liverwort-Hornwort Taxonomy), The Field Museum, Chicago (2009);Congreso Colombiano de Botánica, Nariño, Colombia (2009); Department of Botany, The Field Museum, Chicago (2008); Department of Biology, University of New Mexico (2007); Congreso Latinoamericano de Botánica, Dominican Republic (2006); Department of Biology, University of Panamá (2006); World Congress of Bryology, Venezuela (2004).